Lets add some definition to those grooves.
Hit (toggle) Z so we can see through all the faces. WireFrame.
Now select all vertices toggle A. a few times.
Hit K to do a loop cut.
Select knife exact.
Now try to cut as close as you can, and below the vertices that
you just dragged down. See image.
Hit Enter.

Now take some time to look at your work from different angles in
Object mode. Set smooth. If you want more definition to the groove
bottom, you can go back and redo the loop cut closer. Or drag the
vertices down more from two steps ago. You're the artist.

Okay its time to add some more to the base. You might need to redo
these steps a few times to actually get it. But perseverance will
pay off. And your work will look similar to the image.
Tab into Edit Mode.
Hit (toggle) Z so we can see through all the faces. WireFrame.
Hit (toggle) A to De-select all vertices.
Hit B to box select.
Select all vertices on the bottom of the base.
Hit E to extrude.
Hit Esc. Escape on your keyboard.
Hit S to scale.
Hold in Ctrl and move your mouse to scale outward. Once XYZ 1.1000
Enter
Hit E to extrude.
Hit Z to stay on the z plane.
Hold in Ctrl move the mouse to extrude down twice or -0.2000 on
the global Z. Enter
Hit E to extrude.
Hit Esc. Escape on your keyboard
Hit S to scale.
Hold Ctrl and move your mouse to scale inward Once XYZ 0.9000 Enter
Hit E to extrude.
Hit Z to stay on the z plane.
Hold in Ctrl move the mouse to extrude down five times or -0.5000
on the global Z. Enter.
Hit S to scale.
Hold Ctrl and move your mouse to scale outward twice XYZ 1.2000
Enter

We have built the top base. Huh? Top you say. Yes, we will use
this as the top of the column by duplicating and flipping it. We
will keep the base and add more to it after we get the top.

Hit Tab to go to Object mode.
Hit -minus on the keyboard a few times to zoom out a bit.
Right mouse click on the base to select it.
Hit Shift-D to duplicate . (don't hit enter yet)
Hit Z.
Hold Ctrl and move the mouse upward about six times. Enter see image.

Time to flip the top.
In Object mode.
Right mouse click on the top base that you just created.
Hit S.
Hit -1. Enter. See image.
Of course you could have hit R to rotate and then type 180.

Move the top base up and away.
Right mouse click to select the top.
Hit G to grab then Z and move the mouse up.

Back to finishing up the bottom base.
Right mouse click on the bottom
base to select it.
Hit Tab to go to Edit mode.
Hit +plus a few times on the number pad to zoom in a bit.
Hit (toggle) A to De-select all vertices.
Hit B to box select.
Select all vertices on the bottom of the base.
Hit E to extrude.
Hit Esc. Escape on your keyboard.
Hit S to scale.
Hold in Ctrl and move your mouse to scale outward. Once XYZ 1.1000
Enter
Hit E to extrude.
Hit Z to stay on the z plane.
Hold in Ctrl move the mouse to extrude down four times or -0.4000
on the global Z. Enter

Hit E to extrude.
Hit Esc. Escape on your keyboard
Hit S to scale.
Hold Ctrl and move your mouse to scale inward Once XYZ 0.9000 Enter
Hit E to extrude.
Hit Z to stay on the z plane.
Hold in Ctrl move the mouse to extrude down five times or -0.5000
on the global Z. Enter.
Hit S to scale.
Hold in Ctrl and move your mouse to scale outward. Twice XYZ 1.2000
Enter. see image.